target-ppc: Altivec 2.07: Add Support for R-Form Dual Instructions

target-ppc: Altivec 2.07: Add Support for R-Form Dual Instructions

Some Alitvec instructions introduced in Power ISA Version 2.07 use bit 31
(aka the "Rc" bit) as an opcode but also use bit 21 as an actual Rc
bit.  QEMU for PowerPC typically uses bits 0-5 and 21-30 for opcodes.

This patch introduces a generator macro that injects an auxiliary handler
which decodes both bits 21 and 31 and invokes one of four standard
handlers.  Since the instructions are not, in general, from the same version
of the ISA, two sets of PPC_*/PPC2_* flags are supported.

This patch also introduces a macro to insert two entries into the opcode
table -- one for bit 21 equal to 0 and one for bit 21 equal to 1.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>